1. Field of the invention
The present invention relates to the dental methods and apparatus for the treatment of bruxism, i.e., the grinding of teeth. Bruxism is the abnormal excessive and non-functional nocturnal or subconscious grinding of teeth. Clinically significant bruxism may ruin the teeth and may indicate, or lead to, temporomandibular Joint Dysfunction (TMJ) or Myofascical Pain Dysfunction (MPD).
2. Description of the Prior Art
In TMJ the muscles used for chewing and the joints of the jaw fail to work in conjunction. Due to emotional stress, some people clench their teeth so hard that they jolt their jaw out of its natural position, resulting in TMJ. The misalignment of the temporomandibular joint (jaw joint) causes muscle spasms, resulting in pain in front of the ear and in the head. Thee pain may also spread to the neck, shoulders and back.
The initials MPD have been used to refer to similar terms: "myofascial", "myofacial", "masticatory" or "mandibular" pain dysfunction, see Schwartz, M. Biofeedback: A Practitioner's Guide, Ch 16, pgs. 288-307 (1987).
Typical symptoms of TMJ include cracking or popping sounds from the joint, chronic headaches, and limited movement of the jaw. There presently exist quite a few forms of treatment of bruxism and TMJ. A popular remedy is the insertion of a bit plate made of acrylic. It is worn either at night or 24 hours a day, from three to six months. When worn during the day, it may be unsightly. Other forms of relief, especially from TMJ, are hot and cold compresses, aspirin, muscle relaxants, facial exercise, equilibration (dentist grinds certain teeth to repair the bite), injection of salt solutions or procaine to break up the sensitive points the muscle, surgery to reconstruct the temporomandibular joint (a small percent choose this), massage--to increase the blood circulation and relax the muscle, and biofeedback and relaxation therapies.
An article in the Journal of Consulting and Clinical Psychology, 52: 928-935, 1984, discusses "Biofeedback and Relaxation". In this biofeedback therapy article, silver-silver chloride electrodes were taped bilaterally over the masseteric area (external jaw area). Upon biting down, the digital multimeter increased or the frequency of an audible tone increased. When the patients realize they are grinding their teeth, they stop. The patients were also given general relaxation instructions to follow for 20 minutes each day. Although this biofeedback technique accurately senses the teeth grinding, it is a large device and not portable, so that it cannot be used during the day. The electrodes for example, are three electrodes on the surface of the cheek. Such electrodes are objectionable as they are disfiguring and reveal the patient's problem to others. Consequently, such cheek electrodes are not often used during the day, when they would be most useful. Schwartz, supra, at 292, discusses the use of strip chart recorders for recording facial muscle activity.
The acrylic bite plate is widely accepted in dental practices as a treatment for bruxism. Some patients who have used it appear cured two years later; however, others continue to suffer.
U.S. Pat. No. 4,355,645 shows a device utilizing an electromyographic amplifier and electrodes attached to the patient's masseter and temporal regions to display the EMG potential of the masticatory muscles.
U.S. Pat. No. 3,813,671 shows a flexible mouthpiece used as a multilayer bruxism monitoring device.
U.S. Pat. No. 3,696,666 senses auscultation of the motion and position of the patient's mandible using an external displacement pickup.
U.S. Pat. No. 4,396,019 to the same inventor as herein, incorporated by reference herein, shows a vaginal myograph apparatus using a probe to detect electrical signals from the pubococcygeus muscle of the patient.